Which element is oxidized and which is reduced in the following reaction?
Hg (aq) + HgCl₂ (aq) → Hg₂Cl₂

• A. Hg in Hg(aq): oxidized; Cl in HgCl₂(aq): reduced
• B. Hg in Hg(aq): reduced; Cl in HgCl₂(aq): oxidized
• C. Hg in Hg(aq): oxidized; Hg in HgCl₂(aq): reduced
• D. Hg in Hg(aq): reduced; Hg in HgCl₂(aq): oxidized

Answer: (C)

Verified step by step guidance

1. Identify the oxidation states of the elements involved in the reaction. For mercury (Hg) in Hg(aq), the oxidation state is 0, and for mercury in HgCl2(aq), the oxidation state is +2.
2. Determine the change in oxidation states for mercury. In the reaction, mercury in Hg(aq) changes from 0 to +1 in Hg2Cl2, indicating oxidation.
3. Identify the oxidation states of chlorine in HgCl2(aq). Chlorine typically has an oxidation state of -1.
4. Examine the change in oxidation states for chlorine. In this reaction, chlorine remains at an oxidation state of -1, indicating no change.
5. Conclude which element is oxidized and which is reduced. Mercury in Hg(aq) is oxidized as its oxidation state increases, and mercury in HgCl2(aq) is reduced as its oxidation state decreases.